Process for oxidizing olefins



Jan. 9, 1945. D, GARDNER 2,366,725

PROCESS FOR OXIDIZING OLEFINES Filed Feb. 26; 1941 C2H4O etc.

Hearer To I70 51 Insu laTed Z1 Heafer INVENTOR wow/w Kn? PMWI ATTORNEYSm nted 9, 1945 I PROCESS FOR oxrnrzmo OLEFINS Daniel GardneryNew'Yoi-k,N. Y., assignor to Gardner Thermal Corporation, a corporation ofDelaware Application February 26, 1941, Serial No. 380,622 15 Claims.(01'. zen- 3485) at a temperature safely below that at which the Thisinvention is a novel process for the oxidation of olefins, being thetreatment of unsaturated hydrocarbons of the ethylenic series, typicallyrepresented by ethylene gas, for the purpose of" producing on "anindustrial scale the ethylenic oxide, preferably in a continuousoperation, and

the collectionof such oxide with or without the further step ofconversion othereof to an aqueous or other derivative product such asglycol. While ethylene will be referred tofor illustrative purposes, theprocess hereof is applicable to the treatment of propylene and thehigher homologues, by appropriate variations of temperature, duration,selection of catalysts and other factors involved; The olefin gas may bein strong concentration obtained in known ways, or may be very diluteas, when accompanied 'by other gases from cracking operations. gen maybe supplied as air or in another gas, for example as nitrous oxide. Theingredient gases however should themselves be in a quite pure conditionand free from moisture or other agents which might interfere with orreduce the efll-ciency of the process.

In a copending applicatiomserial No. 380,284,

filed February 24, 1941, has been disclosed 8. Drooess for treatment ofunsaturated hpdrocarbons,

carried out in a non-acid liquidbath, preferably an organic liquid oralkaline reaction.

An object of the present inventionis to provide a practical and usefulliquid bath system for this subject, wherein the bath is of acidreaction and comprises preferably a plentiful inorganic or mineral acid.A particular object is to permit operations at relatively lowtemperaturesso as toyield' the desired oleflnic oxides without danger ofdis- The necessary oxy- I integration by isomerization or otherwise,while vmay firstbe recited as follows. The underlying principle may bedescribed as the process, which may be continuous, of oxidizing anolefin, which process comprises conducting streams of gases containingrespectively the olefin and the oxygen,

, supplied in equimolecular proportions i. e. substantially accordingtotheir combining weights,

; and passing each of these through a hot bath of a suitable non-aqueousliquid wherein is dispersed or dissolved a catalyst eflectlve to promotethe reaction for the combination of the olefin and the oxygen to formthe'olefinic oxide, carried out olefin or its oxide is liable todisintegrate, asby isomerization or polymerization. By non-aqueous ismeant that the bath should contain no appr ciable q antity of freewater, not referring to the water of combination which is a component ofcertain acids. The characterizing features include the following. Thebath vahicle is of strong acid character, as a concentrated solution ofan acid, preferably-a mineral acid, and containing no free water. Theacid, as sulfuric acid, is adapted to take part in the reaction by firstcombining with the olefin to form an intermediate product, asethylsu'lfuric acid, which next yields the olefin for combination withthe oxygen. The ability of such'a bath to absorb chemically a givenolefin usually ceases within a certain temperature range above which'thereaction reverses, so that the bath should be well below such transitiontemperature. Under these conditions the firstreaction step occursreadily, and the catalyzer is for promoting the second step of the de-'scribed indirect oxidation.

This invention then has to do with the catalytic oxidation of 'ethylenichydrocarbons, particularly as taking place when passing a current of airor oxygen through an alkylsulfuric compound, such as 'saidethylsulfuricacid, present or dissolved in an excess of sulfuric acid, thealkylsulfuric compound being continuously formed by interaction betweenthe ethylenic hydrocarbon and the sulfuric acid, and thereuponcontinuously giving up its ethylene component to unite with the oxygen.

While sulfuric acid HzSOrwas mentioned it is but a preferredrepresentative of acids available for the reaction bath of thisinvention, such as phosphoric, arsenic, boracic and selenic' acids;

telluric .being operative but too'costly. These acids may be classed asexamples of the group of mineral acids, but not to the exclusion ofother kinds of acids which can first takeu'p the olefin and thenyield itto oxidation.

It is advantageous to add auxiliary agent or salts to the bath, forexample, to add to sulfuric acid one or more of the acid salts NaHSO4 orKHSO4. ,These are-found to assist the taking up of the olefin, possiblyby active or. mass action.-

Platinum black or sponge is an instance of a suitable catalyzer, andothers will be enumerated after reciting an illustrative example of theinvention; remembering that any catalyst is subject. to fatigue, andthat occasional switching of the process from one bath to another isadvisable to permit refreshing or activating th in this and'otherrespects 7 "L erization or otherwise, which in the case of operatingalso-"to regenerate the following formula:

bath.

' 'rhe supplied ethylene gas, andasweu the oxygen-containing gas,nitrous oxide, maybe preheated while being conducted tothe'furnace or ireaction vessel. Thelbath being maintained between about 145 and 155,'withoutside limits of 140' and 160, the preheating of the supply'gases.may beffor example to 170. The bath maybe -in the form of a shower, orpreferably a column of the liquid vehicle-through which the respectivegases may be passed by 'blowlng .them"into the bottom of the bath toascend therein in the form of fine bubbles adapted efiectivelyt'ocohtact the bath liquid and other agents. I

Theltreatment bath'may consist of pure sulfuric acid, and by the jointascent through the 20 bath of the respective gases there may be. somedegree of direct combinatiomor oxidation of the ethylene, but in themain the reaction, isja twofold one. In the flrststep the ethylene makescombination'with part of 'the'acid, which loses to the ethylene one atomof hydrogen in the process.

Thus is formed the intermediate. product ethylsulfuric acid or acidethyl sulfate, which is an ester and constitutes one of the'alkyl sulfurcompounds. The temperature is preferably between 145 and 155, safelybelow the transition temperature of about 160 above which the first stepof vices 22; and any known means may be employed for preheating thegases between blowers and dischargers, such as the heater 23 shownconven tionally as a box through which the flues extend.

The productgases are conducted from the fur-'.

- .nace or vessel by an outtake pipe 25 leading to a shown in the formof ultraviolet tubes 21 positioned within the reaction space.

. Manifestly the gases outgoing at pipe 25 could be recirculated backthrough'intake pipe l5 or for more exhaustive reactions; and in such wayT the process could be discontinuous'if desired, or

' batch by batch.

the reaction can not occur; and is below the break-up point at whichthere is a tendency of the ethylene or its oxide to disintegrate byisom- Byway of assisting the step of combination of ethylene andsulfuric acid there may be added to the bath an. auxiliary agent orsalt, for which the acid salts, sodium or potassium bisulfate, or T 1vailing typeset industrial installations that are .C2H5QSO3H+OC2H4Q+TI2$OA The product gas or ethylene oxide bubbles up and out of thebath, along "withthe various inert, or idle gases withwhich the ethyleneand oxygen the sulfuric ac d by supplies-were entrained; and the entirestream of outflowing gases may bapassed-to a suitable point for the,collection of the ethylene oxide or for its conversion into derivativeproducts.

The example recited isillustrated by the single diagrammatic figure ofdrawing with legends indicating suitable materials and temperatures. Theliquid bath l0 represents either a spray or a column as shown, throughwhich the supply gases] must flow. The furnace or vessel ll, ofnon-corrosive material, contains the reaction chamber or space withinwhichis maintained the bath. 6

The olefin is shown fed bysupply pipe l3, blowerl4 and passage or fluel5 to a discharge! vI Bshown as a perforated extension of the pipe. "Theoxy- 7 Supplemental explanations The different catalysts to beenumerated all have in commonthat, when dispersed in hot sul- I furicacid or another suitable acid solution, such as molten bisulfate ofsodium or potassium, they act catalytic'ally within a definitetemperature range and thereby contribute to the oxidationof any of theethylenic hydrocarbons. By this process, and these catalysts,-eitherpure ethylenic hydrocarbons' can be submitted to oxidation, or'the samehydrocarbons mixed with other hydrocarbons; as with gases obtained bymodern 011 cracking processes or those resulting from coke-oven rorsimilar operations. e v

For the most part the indicated catalysts have already been made use ofin various chemical processes; butit-is believed to be novelftc applysaid catalysts in the process" or system herein disclosed or inthe'conditions as already stated or summarized; the matters of noveltybeing or. practical value since they afiord an economic advantagawithoutneed of discarding the prenot only costly but often complicated.- Thevar- 'num black in'formof a suspension in concentratthe metal in veryfine state for suspension or colloidal dispersion therein. The oxidationof ethyl- -160 CL, and goes as follows:

gsoLczHmH-F02*2OHQCHmdHLHSO4 ene i carried out at a. temperature belowabout By treatment withpotassium hydrate the so ob tained productgivesethylene p d in the same oncmcrnrrsomzggd-s :i cmcmp+ms04+2mo Ifdesired, the ethylene oxide can be'introduced into water in order toobtain ethylene glycol.

(2) Palladium black in very finely divided state dissolves inconcentrated sulfuric acid, thus givgen, as air or nitrous oxide,is-supplied by pipe I 8 and driven by blowerQlQ through passage or flueV 20 to perforated-discharger 2|. The dischargers are placedlowtodeliver the gas streams as'bub-i blesvascending in, intimatemixture through the fling-a certain advantage over platinum black.

Otherwisetheactionjsa very much similar one.

I (3),.Silver sulfate. use of silver salt': I more particularly ofsilver sulfate, is well estab-'= lished for catalysisfor instance forthe produc-y tion of esters, as by action-upon halogen alkyls." Silversulfate-is soluble in concentrated sulfuric F ascavas acid, affordinggood results of oxidation, even at n a temperature of up to 250. a

(4) Copper sulfate works in similar manner I to silver sulfate: but ithas a lower melting point.

(5) Thallous sulfate. This salt functions also like silver sulfate.However, it is well soluble only in dilute sulfuric acid, and besideshas the drawback of going over into thallic sulfate.

(6) Manganous sulfate is soluble in concentrated sulfuric acid; and canbe easily incorporated in the acid in a suitable quantity. It giveslower yields when used as a catalyst.

(7) Ferrous sulfate is a well known catalyst in certain organicreactions. This is a cheat! acid, HzSeOa, which corresponds to sulfuricacid;

and is particularly appropriate in an oxidizing bath of selenic acid,and dissolves also in sulfuric acid. The catalytic'action is marked, butit is necessary to workat the lowest practical temperature, below 260,to avoid decomposition ,,and carrying away of the salt.

(10) Silver nitrate. Like silver sulfate, the nitrate'has already beenfrequently used in orthereby practicallyextracted from the supply gasesand rendered available forindustrial purposes.

Under the principles of this invention the bath must be acid; and whilestrong acidity is preferable, this may be weakened so long as it remainsliquid up to the hot reaction temperatures used, such as about 160 or200; and as instances within this suggested equivalent may be men-'tloned molten salts, as .NazSOs or mSOu, or a stable hydrocarbon, liquidand acid, operated under hot temperature and with the catalystincorporated.

What is claimed is:

1. The process of oxidizing ethylene or other olefin comprisingconducting supply streams of.

- gases containing respectively the ethylene and the oxygen supplied insubstantially equimolecularproportions,passingthe ethylene and'theoxygen' gases into and through a substantially nonaqueous liquid bath ofa concentrated mineral acidof the group consistingoffsulfuric,phosphoric, arsenic, boracic and selem'cacids, in

ganic processes. Its great advantage consists in its low melting pointof 212. It is easily incorporated ,in concentrated sulfuric acid.

(11) Lead nitrate has given satisfactory results as a catalyst. Whenincorporated in concentrated sulfuric acid, it partly goes over intolead sulfate, which precipitates in the form of a fine powder, since itis only slightly soluble.

(12) Thallous nitrate is an excellentcatalyst and has a relativelylowmelting point, but is poisonous. The salt otherwise acts likethallous sulfate, but permits working at lower'temperatures, which isalways an advantage when'work ing 'with .ethylenic hydrocarbons andtheir de-' rivatives. s

The above twelve series of salts, includingj other sulfates, nitratescatalysts were among a long I which bath is disperseda catalyzer whichis stable in the acid bath, the oxidation being in two reaction steps,theethylene first combining with the acid to form ethylsulfuric acid asan intermediate product, and the intermediate product then yielding theethylene to combine with the oxygen as ethylene oxide while the acid isregenerated, the catalyzer being a substance other than the bath acidacting to promote the.

second step, and the temperature being maintained at a reactiontemperature well below that of liability of the ethylene or its oxide todisin tegrate, and within a temperature range in which the first stepcan occur, between about 145 and 155.

2. The process of oxidizing an olefin comprising conducting streams ofgases containingrespectively the olefin and the oxygen supplied insubstantially equimolecular proportions and sub stantially atatmospheric pressure, .passing the olefin and the oxygen through aheatedbath of substantially non-aqueous concentrated acid liquid wherein isdispersed a catalyzer other than the bath acid which is stable in thebath and acts'to promote therein the combination of the olefin andtheoxygen to form theolefin oxide, a

andn aintaining said bath at a reaction tem- 'perature between about 140and 160 C.

3. The continuous process of oxidizing an I olefin comprising passingpreheated streams of and selenates thatwere tested, others of which.

were not satisfactory. The twelve have been especially mentioned asillustrativecatalysts be-;.

cause, they allgave satisfactory results, buttheirmention is not toexclude others that trial may I show to be useful.

. Since at the bath verted in passingthrough the reaction zone, andsinceat the speed and shortduration of passage they are not subject tosulfurationggas'es is suing from modern cracking processes or'from'coke-ovens can be passed directly; through the,

above described system, in their "diluted condi- V temperaturesdesignated sat-'1 urated hydrocarbons are not attacked' g c s gasescontaining respectivel 'the olefin andthe oxygen through a heated bathof substantially non-aqueous concentrated acid liquid wherein isdispersed a catalyzer other than the bath acid jwhich'isstable in thebath and acts to promote -therein'the combination of the olefin and theoxygen to form the olefin Oxide-,and maintaining said bathat a reactiontemperature well below thedisintegration temperature of the olefin tion,without fear or impairingthe reactions or,

contaminating the products desired. In other words, under the describedprocess conditions, only the ethylenic or other unsaturated hydrooxide."w

- 1 '4. The process of] oxidizing an olefin comprising conductingstreamsof gases containingrespectively' the olefin and the oxygen, passing theolefin .and the Oxygen through a heated bath of substantiallynon-aqueous concentrated acid liq uid wherein is dispersed acatalyzerfwhich is stable in the acid bath, thereby to cause a-two- -1stage reaction, the olefin first forming an inter carbons are attacked,these 1 taking part in; the j chemical changes and becoming rapidlytrans-.

7 formed intothe respective oxides or-glycols. The i entire content ofthe ethylenic compounds-is mediate compound withthe bath acid whichcompound thereupon yields the olefin for com binationwith the oxygen;and maintaining said bath ata reaction temperature well below theytemperature of reversal of the first reaction stage; the catalyzerbeing. an added substance other than the bath acid adapted to promotethe second reaction stage with the olefin oxide as a product, and suchsecond stage acting to regenerate the acid of the bath.

,5. A process as in claim 2 and wherein the reaction bath is of an acidliquid containing an acid of, the group consisting of the mineral acids,sulphuric, phosphoric, arsenic, selenic.

6. A process as in claim 2 and wherein the non-aqueous reaction bathconsists of sulfuric acid.

7. A process as in claim 2 and wherein the nonaqueous reaction bath isof an acid liquid containing selenic acid.

8. A process as in claim 2- and wherein the non-aqueous reaction bath isof an acid liquid comprising molten acid salts of the group consistingof sodium sulfate and potassium sulfate.

9. A process as in claim 4 and wherein the non-aqueous acid bath isfortified with; an auxiliary agent or acid salt adapted to promote thefirst reaction stage, selected from the group consisting of sodiumbisulfate, potassium bisulfate and a mixture of the two.

10. The process as in claim 4 carried out with a catalyzer which is ametal salt soluble in the non-aqueous bath and selected from the groupconsisting of the sulfates of silver, copper, iron, thallium, manganese,tellurium and nickel.

11. The process as in claim 4 carried out with a catalyzer which is ametal salt soluble in the non-aqueous bath and selected from the groupconsisting of the nitrates of silver, lead and thallium.

12. The process as in claim 4 and wherein the catalyzer is palladiumblack.

13. The process as in claim 1 and wherein the catalyzeris of the groupconsisting of the sulfates of silver, copper, iron, thallium, manganese,,tellurium and nickel.

14. Theprocess of oxidizing an olefin comprising conducting streams ofgases containing respectively the olefin and the oxygen passingtheolefin and the oxygen jointly through a bath of a substantiallynon-aqueous acid liquid wherein is dispersed a catalyzer which is stablein the acid bath and acts to promote the oxidation hot reaction, andmaintaining said bath at a reaction temperature Well below thetemperature of disintegration of such oxide, such catalyst beingselected from the group consisting of the sulfates of silver, copper,iron, thallium, manganese, tellurium and nickel. I

15. The process of oxidizing an olefin comprising conducting streams ofgases. containing respectivel the olefin and the oxygen supplied inequimolecular proportions, passing the olefin and the oxygen jointlythrough a bath of a substantially non-aqueous acid liquid wherein isdispersed a catalyzer which is stable in the acid bath and acts topromote the oxidation hot reaction, and maintaining said bath at areaction temperature well below the temperature of disintegration ofsuch oxide, such catalyst being selected from the group consisting ofthe nitrates of silver, lead and thallium. 1

16. The process of oxidizing. an olefin comprising conducting streams ofgases containing respectively the olefin and the oxygen, passing theolefin and the oxygen jointly through a bath of a substantiallynon-aqueous acid liquid wherein is dispersed a catalyzer which is stableinthe acid bath and acts to promote the oxidation reaction, andmaintaining said bath at a hot reaction temperature well below thetemperature of disintegration of such oxide, and below about to C.; suchcatalyst being palladium black.

DANIEL GARDNER.

